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System Hacking - Definition, How to Hack & Phases

What is System Hacking?

System hacking is defined as the compromise between computer systems and software to access the target computer and steal or misuse their sensitive information. The malware and the attacker identify and exploit the vulnerability of the computer system to gain unauthorized access.

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Hacking Linux system

Linux is an operating system based on Unix OS created by Linus Torvalds. It is assembled over the model of open-source software development and distribution.

Hackers use varied techniques to hack into Linux systems:

  • Hacking Linux using the SHADOW file.
  • Another technique used is bypassing the user password option in Linux.
  • Other technique includes detecting the bug on Linux distribution and taking advantage of the same.

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Hacking Mac OS

For hackers, hacking a Mac OS is as normal as hacking any other operating system. Various ways that hackers adopt to hack into Mac OS are:

  • One Python command to bypass anti-virus
  • One Ruby command to bypass anti-virus
  • One Tclsh command to bypass
  • Use recovery mode to extract and brute-force the hash
  • Use single-user mode to configure a backdoor
  • Connect to backdoors from anywhere.

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Hacking Android phone

Android system hacking is done in the following ways:

  • Install malware or a Trojan in the victim’s phone and control it remotely via your own device.
  • Creating a shell terminal with admin access in the victim’s phone.
  • Using Spynote can also be one of the modes of android hacking.
  • Using ADB (Android Debug Bridge)
  • Spy apps
  • Stagefright exploit
  • Keyloggers- Kikde iOWL and Shadow- Kids keylogger

Hacking Windows

Out of the several tried techniques of hacking Windows systems, the one that is usually preferred by hackers is Social Engineering. Once the hacker finds a Windows computer open, he can easily modify the existing password and give a new one thereby taking control of the same, without the owner being aware.

Ethical hacking vs Penetration testing:

Ethical Hacking Penetration testing
Hacking the system in an ethical way to discover vulnerabilities of the system. Formal procedure to discover security vulnerabilities, flaws and risks.
Conducted to identify flaws and prevent real time hacking. Conducted to strengthen their corporate defense systems.

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Phases of System Hacking

There are five phases in penetration testing. It includes –

  • Reconnaissance – Majorly used to gather data
  • Scanning – Used to gather further intelligence on the data
  • Gaining access – Takes control of one or more network devices to extract data.
  • Maintaining access – Gains more data from the targeted environment
  • Covering tracks – Remove traces of detecting the attack.

There are various concepts of hacking such as the phase of pen-testing, footprinting, scanning, enumeration, system hacking, sniffing traffic, and so on.


Footprinting, also known as reconnaissance, is used for gathering all possible data about the target system. It can be active or passive. The collected data is used to intrude into the system and decide the attack types on the system based on security. A lot of information such as domain name, IP address, namespace, email id, location, history of the website can be found by this method.

Footprint and Scanning Tools

Several footprinting tools are used to gather information such as –

  • Crawling – Surf the internet to gain information
  • Whois – lookup of the website to get information like email, registration, etc.
  • Search engines – Google, Bing, and other search sites to get data
  • TracerouteTraceroute is Used to trace a path between the user and the target system on the networks.
  • Netcraft – tool to gather information about web servers on both server and client sides.
  • Nslookup – Querying DNS server to extract information
  • The Harvester – Used to catalog email and subdomains.

Scanning tools such as –

  • Nmap – Used for scanning and used to find open ports of the target.
  • Nessus – To find vulnerabilities in the ports.
  • Nexpose – Similar to Nessus

Penetration testing/exploitation tools such as –

  • MEDUSA – Used to gain authentication service in the target machine.
  • Hydra – To break authentication system
  • Metasploit – Used to exploit the system.

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Network scanning

Scanning is the second stage of information gathering where the hacker tries to do a deep search into the system to look for valuable information. Ethical hackers try to prevent organization’s attacks by using this network scanning effectively. The tools and techniques used for scanning are –

  • Crafted packets
  • TCP flags
  • UDP scans
  • Ping sweeps

The hackers try to identify a live system using a protocol, blueprint the same network, and perform vulnerability scans to find weaknesses in the system. There are three types of scanning –

  • Port scanning – Used to find open ports
  • Network scanning – Used to find the IP address
  • Vulnerability scanning – find weaknesses or vulnerabilities

Gaining Access

Here the hacker uses different techniques and tools to gain maximum data from the system. They are –

  • Password cracking – Methods like Bruteforce, dictionary attack, rule-based attack, rainbow table are used. Bruteforce is trying all combinations of the password. A dictionary attack is trying a list of meaningful words until the password matches. The rainbow table takes the hash value of the password and compares it with pre-computed hash values until a match is discovered.
  • Password attacks – Passive attacks such as wire sniffing, replay attack. Active online attacks such as Trojans, keyloggers, hash injection, and phishing. Offline attacks such as pre-computed hash, distributed network, and rainbow. Non-electronic attacks such as shoulder surfing, social engineering, and dumpster diving.

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Maintaining Access

Once you gain access to the system using various password cracking methods, the next step is to maintain the access in the system. To remain undetected, one has to secure their presence. To secure the hacker can install a hidden infrastructure to keep access to the backdoor open. Trojan horses, covert channels, and rootkits are used. A trojan horse provides access at the application level, used to gain remote access. A covert channel is where the data can be sent through secret communication tunnels. A rootkit is a malware type that hides from the system, they conceal to bypass the computer security measures.

Covering Tracks

All the traces of attack such as log files, intrusion detection system alarms are removed to cover the tracks. Removes all files and folders created, modifies logs and registry once the hacker leaves the system. Using reverse Http shells and ICMP tunnels also helps to cover tracks.

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Protecting your system from Hacking

Following preventive measures can be taken to combat hackers:

OS Updates

Frequently updating the operating system keeps hackers from accessing your system through vulnerabilities in outdated programs. 

Security Programs

Downloading and installing up-to-date security programs including anti-malware helps in boosting the security level of your system 


It can be used to erase all your personal traces, files, folders, etc. on the hard drive, in case of reselling your device. 

Smart Emailing

Quick searches on the subject line or the recipient helps in combating phishing practices.


Keeping sensitive data off the cloud curbs the risk of exposure to hacking.

Online Security tools

These can be used to protect the computer systems from hackers through in-built identity theft protected online security tools.

Network strengthening

Strong encrypted passwords and VPN (Virtual Private Networks) allow protection from cybercriminals breaking into your system security.

Internet Security Suite

Adopting a full-fledged internet security suite for your organizations or personal systems is one of the most trusted solutions to prevent cyber attacks.


It is advisable to train the staff of the organization to thoroughly check the links and e-mail addresses before clicking on them and mails. Keeping the employees informed about cybersecurity threats, modes and precautions by conducting training sessions has become crucial nowadays.

Endpoint Protection

There are networks that are remotely bridged to devices. Laptops, computers, and mobile devices are connected to corporate networks paving the way for security threats. Such paths need endpoint protection software.


Installing a firewall has been proven to have defied major cyberattacks. Firewalls tend to block any brute force attacks meant for the computer system before they could damage the network or files.

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About the Author

Senior Reserch Analyst - Cloud Computing

Arpit has years of experience working with top-tier tech companies and has developed a plethora of knowledge in Data Analysis and Machine Learning. He currently holds the position of Senior Research Analyst in Cloud Computing. His passion for writing extends beyond the technical world, crafting profound narratives that bridge the gap between complex concepts and accessible understanding.